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M1A Reloading Question

Discussion in 'Handloading and Reloading' started by molonlabe, Aug 24, 2004.

  1. molonlabe

    molonlabe Well-Known Member

    Im not sure where to put this but I think it will get more exposure in rifle.

    I have a load that works very good for hunting and match shooting. 168gr Sierra match king with 40 gr of IMR3031. (I use the game king for hunting). This makes <1 in groups with My M1A NM and in the Bolt Ruger M77VT it can hold ½ moa. The problem I noticed is the primers is flattened and slightly cratered coming from the M1A. I did switch to federal match but my next round I will go back to the CCI because they are harder. I don’t believe it is over pressured because the base does not look bulged. The case definitely stretched and will need to be trimmed again but that is expected since it is mil spec. I know flatting of primers isn’t a good indicator of pressures but nonetheless should be heeded.

    Since I never noticed this before my question is this a problem? Is the powder too fast since it is slightly faster than 4064 for the firearms (M1A)operating curve. The groups are good and the bolt action has no problem or flat primers. Thanks for any help.
  2. waynzwld

    waynzwld Well-Known Member

    I don't know what to tell you. Most starting loads show 37grs of 3031 and max loads at around 41grs. I reload for many different rounds and some flatten the primers. Some factory loads do that too, BUT, I use a chronograph to verify that my handloads are within the normal velocity range for that cartridge. Without chronographing the velocity, you are just guessing what is going on. You might try backing down to 38grs and see what the primers look like and work back up from there.
  3. Mark whiz

    Mark whiz Well-Known Member

    Most M14/M1A folks consider 3031 to be a little too fast for use in a gas-operated rifle. For M1A use I've found my best accuracy with 4895 and 168SMKs and when dropping down to 150gr bullets I've done well with RL-15 and with ball powders Win748 or Hodgdon BL-C(2).

    I HAVE noticed that when using ANY stick powder, my M1A tends to flatten and dimple the primers a bit, but not with ball powder loads - go figure. :rolleyes:

    BTW........."standard" loads for 4895 run from about 41 to 42.5gr when using mil-spec cases and 168SMKs.
  4. molonlabe

    molonlabe Well-Known Member

    My reloading manual says
    38.0 = 2400fps
    39.6 = 2500fps
    41.3 = 2600fps
    So I am a bit close to the maximum. Maybe the burn rate of the powder and the pressure curve changes things too much for the gas system. I do have a chronograph and I will check it. that would probably give me the answer to the above if the velocity matches closely with published data.

    4895 does say 39 to 43.4gr max. Unfortunately I don't have that powder but I will try it. Meanwhile I'll back off to 38 gr. and look at the result lest I beat the crap out of the rifle and op rod.
  5. Mark whiz

    Mark whiz Well-Known Member

    When you pullout the Chrono...............just for the record, the Mil-Spec for 168gr match rounds for the M1A is a MV of 2550fps and 2750fps for 150gr rounds.

    Load to that spec and then see what your primers look like.
  6. Steve Smith

    Steve Smith Moderator Emeritus

    Try Varget.
  7. Grump

    Grump Well-Known Member

    3031 is considered the fastest acceptable in the M` in .30-06, so I've considered it to be also acceptable in the M1A. Remember, it has a self-adjusting gas system, superior to all the adjustments available in an FAL when going to light loads. The "limit" on 3031 is that chamber pressures will be max at a few FPS slower than with 4895, and a bit more so when compared to 4064.

    You never told us what cases you are using. That can make a difference!:)

    Visually compare the clearance between your firing pin nose and the boltface on your bolt gun and your M1A. Sometimes cratering is caused by the primer having room to flow into a gap, or by some factor making the firing pin easier to push back into the bolt==even with normal-pressure loads. That last one is unlikely based on how the M1A bolt and hammer interact, but look at that anyway--along with your firing pin protrusion (short FP throw can mimic primer cratering).

    As far as flattening goes, what is the clearance between the headspace of your reloaded ammo and the headspace of your two rifles' chambers? SAAMI-min ammo in a NATO-max chamber can be a bit loose--.015 IIRC, or is it .0015..whatever, I measured primer setback on light loads at something ending in 015--and allow the primer to set back and expand a bit radially before the case finishes sliding back against the boltface. Safe loads will then *appear* to have pressure-flattened primers. Anyway, compare the chambers of the two rifles, since the ammo variable is the same.

    A sure sign of high pressure is good quality cases setting back into the ejector hole and/or the opening at the extractor. You're above 60,000 or more before that happens. All bets are off with soft brass. No brass will pick up machine marks in your chamber under exess-pressure loads if the chamber is too smooth.
  8. molonlabe

    molonlabe Well-Known Member

    All of the fired cases were Lake City. The cases show no ejector hole or extractor marks. For the most part they look pretty pristine other than a lot of circular chamber marks that I never really noticed before. They clean up OK in the tumbler. And I did clean the chamber with a chamber brush last cleaning.
  9. 1911Tuner

    1911Tuner Moderator Emeritus


    My favorite self-shucker!

    Mark Whiz nailed this one smack on the hittin' place. Try
    41.5-42.5 grains of 4895...IMR or Hodgdon. The data is
    interchangeable for the most part.

    As for flat primers with extruded powders and not with ball...like Olin 748...Ball powders, and particularly Olin-Winchester ball powders produce identical velocities with lower pressures than the extruded powders like
    IMR powders. Acording to some of the figures that I've seen, the pressures can be dramatically lower...as much as 10,000 CUP for a given
    velocity level. The main problem that I've had with Olin powders is that
    the velocities aren't as consistent unless the loading densities are high, and magnum primers are used. This normally makes for higher than expected velocities when the acceptable accuracy level is reached. Of
    course, the pressures also go up...but they'll still usually be lower than
    accurate loads with stick powders.

    The downside is that the high calcium carbonate content of the ball powders make more frequent cleaning necessary. The fouling builds up in the throat area, and can be extremely hard to remove if ignored for too many rounds. The stuff can become harder than the barrel steel.
  10. atek3

    atek3 Well-Known Member

  11. Grump

    Grump Well-Known Member

    OBTW, the military velocity standards are instrumental at 78 FEET, or 26 YARDS, and the tolerance is plus/minus 30 fps, all at some standard temperature colder than my usual shooting sessions. Add about 40 fps if your screens are at only 10 feet.

    Spherical powders by every maker are more temperature sensitive than stick powders. Notice that none of the Hodgdon "Exteme" series is a spherical powder?
  12. Steve Smith

    Steve Smith Moderator Emeritus

    I agree with Grump, if you are going to be outdoors all day in the heat the spherical/ball powder is bad ju ju.
  13. molonlabe

    molonlabe Well-Known Member


    Thanks for the link. It provides a lot of information that I haven’t seen before including the fact that IMR4064 is the fastest powder they recommend. IMR3031 is faster according to the charts. I have a good supply of 4064 so I may work up some rounds and check the effect.\ until I can get some 4895.
  14. HankB

    HankB Well-Known Member

    I've found that IMR 4064 gives me noticeably tighter groups in my match M1A than does the "traditional" powder, IMR 4895, when loading 168 SMKs. I've always been under the impression that 4064 is just about as slow as you want to go for a gasgun.

    Supposedly, Federal used a non-cannister version of 4064 in loading their Gold Medal Match ammo when introduced . . . don't know if they still do.
  15. Grump

    Grump Well-Known Member

    Well, does once-fired factory ammo do that too?:eek: If so, you may disregard. If the factory stuff doesn't pick up annular rings of machine marks from your chamber, AND the reloads' velocities are within expected values for THAT powder (especially when compared with factory), then I'm much more willing to say you do have high chamber pressure.

    If the factory stuff also gets ringed on the first firing, have a gunsmith check your chamber for excessively deep machine marks = lack of proper finish polishing.

    I first experienced that problem with .30 carbine load, lead bullets, and cases that were too long. The mildly crimped case mouths pinched the bullets in the throat and had nowhere to expand on firing. When GI brass in a 40,000 CUP chambering get ribs from the machine marks all the way back to the web, you notice.:what:

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